1. University of Padova, Department of Information Engineering, Via Gradenigo 6B, 35131 Padova, Italy
2. CNR-IFN UOS Padova, Via Trasea 7, 35131 Padova, Italy
3. National Institute for Standards (NIS), Alharam St. Tersa, 12211 Giza, Egypt
4. Italian National Research Council–Institute for Photonics and Nanotechnologies (CNR–IFN), Via Cineto Romano 42, Rome 00156, Italy